Beta-adrenergic receptor blockade attenuates the electronic uncoupling induced by coronary artery occlusion

Nine dogs (n=9) with healed anterolateral (L1Da) infarction, were chronicully instrumented for myocardial electrical impedance (MEI) measurements, and subjected to brief (2min) LCXa occlusions with (BETA) and without (CTRL) beta-adrenergic receptor blockade. Scar tissue (LADu) had significantly lower ME1 (373.5H8.8R) than normal (LCXa) myocardium (CTRL: 548.899.012, BETA: 532.2G4.1Sl). MEI increased signQicantly after 2min LCXu occlusion (CTRL and BETA). However, beta-adrenergic receplur blockade significantly attenuated the magnitude of such increase. In control conditions (CTRL) MEi increased 4..5H.8% (21.3&7.a), while wirh beta-blockade if changed only by 3.441.8% (15.66.751). In a I-D cable model of propagating action potentials (Luo-Rudy formulation), such reduction of the ischemic electronic uncoupling prevented conduction block ut the ischemic/scar interface.